Hydraulic pumps

ABSTRACT

THE PUMP COMPRISES A ROTATABLE CYLINDER BLOCK IN WHICH CYLINDERS ARE PROVIDED. PISTONS SLIDE IN THESE CYLINDERS. EACH VARIABLE VOLUME CYLINDER CHAMBER COMPRISES AN ADMISSION PORT AND A DELIVERY VALVE. A COUNTERBALANCING SHOE IS DISPOSED COAXIALLY WITH EACH CYLINDER AND BEARS AGAINST A REGULATING PLATE. THE REGULATION OF THE DELIVERY RATE IS ENSURED BY A GROOVE, PROVIDED IN THE REGULATING PLATE, AND EXTENDING OVER AN ARC OF 180*.

4 Sheets-Shes?l l Jan. 19, 1971 M- SCHOTT ETAL HYDRAULIC PUMPS Filed Jan. 29, 1959 Jan. 19, 1971 M, SCHQTT EVAL 3,556,683

i l HYDRAULIC PUMPS Filed Jan. 29, 1969 4 sheets-sheet z Jan. 19, 1971 M. SCHOTT EVAL HYDRAULIC PUMPS 4 Sheets-Sheet 3 Filed Jan. 29, 1969 Jan. 19, 1971 M, @H0155m.

HYDRAULIC PUMPS @Fbf Filed Jan. 29,l 1969 4 Sheets-Sheet 4.

United States Patent O 3,556,683 HYDRAULIC PUMPS Marcel Schott, Colombes, and Bernard Vauvelle, Houilles, France, assiguors to Societe Nationale dEtude et de Construction de Moteurs dAviation, Paris, France Filed Jan. 29, 1969, Ser. No. 794,887 Claims priority, application France, Jan. 30, 1968,

im. el. F0411 1/02, 49/00 U.S. Cl. 417-270 Claims ABSTRACT OF THE DISCLOSURE This invention relates to hydraulic pumps of the type which comprise, on the one hand, a rotatable cylinder block in which are provided cylinders of axis parallel to the axis of rotation of the cylinder block and which are regularly distributed about this axis, and on the other hand, pistons which slide in these cylinders. This invention is particularly, though not exclusively, applicable to hydraulic pumps intended to be mounted in aeronautical or aerospatial equipment; such hydraulic pumps should possess the characteristics of lightness, of reliability of operation and of correct behaviour at relatively high temperatures.

Thus the chief object of this invention is to provide such hydraulic pumps which fulfill the requirements of practice, particularly with respect to their lightness, their reliability of operation and their behavior at relatively high temperatures.

A hydraulic pump according to the invention comprises:

A casing,

A cylinder block rotatable about a first axis and in which are provided cylinders of axis parallel to this first aXis and regularly distributed about this first axis, and

A wobble plate rotatable about a second axis intersecting the first axis and forming with the first axis an obtuse angle.

The hydraulic pump also compresses a connecting means for positively connecting in rotation the cylinder block and the wobble plate,

Pistons slidable in the cylinders and each coupled to one of the two ends of a rod whose other end is coupled to the wobble plate,

Admission ports and delivery valves for serving, respectively for the admission and for the delivery, each of the variable volume chambers defined by a cylinder and the corresponding piston,

And drive means for driving in rotation the unit constit'uted by the cylinder block and the wobble plate.

This pump further comprises, in order to permit the delivery rate of the liquid delivered to be varied between a maximum value and a minimum value, and

A rotatable collector rigidly connected to the cylinder block and provided with a delivery conduit coaxial with the first axis, this delivery conduit being in communication with each of the variable volume chambers when the delivery valve is open, this delivery conduit being connected, by the intermediary of a sleeve ensuring annular liquid tightness, to a delivery orifice coaxial with the first axis and providing in the casing.

A regulating plate is mounted perpendicular to the first axis and so as to be able to turn about this first axis, this regulating plate being provided with 1a groove connected t0 low pressure and ex-tending Over a circular arc of at the most.

Counterbalancing shoes, each corresponding to a variable volume chamber, are mounted in cylindrical housings permanently connected to the corresponding variable volume chamber, each of these counterbalancing shoes being provided with an orifice, each of these counterbalancing shoes bearing against the regulating plate such that the orifices pass in front of the groove of the regulating plate, directly opposite this groove.

A control means is included for turning the regulating plate from a first extreme angular position for which the groove is in communication solely with the variable volume chambers in which the pistons are performing their admission stroke, this first extreme angular position cor responding to the maximum value of the delivery rate of the liquid delivered by the pump, to a second extreme angular position for which the groove is in communication with all or some of the variable volume chambers in which the pistons are performing their delivery stroke, 4this second extreme angular position corresponding to the maximum value of the delivery rate of the liquid delivered by the pump.

The invention includes, apart from this principal feature, lcertain other features which are preferably used at the same time and which will be more explicitly described hereafter.

In any case, the invention will be well understood with the aid of the following complementary description and the accompanying drawings, which complementary description and drawings are given merely by way of example.

FIG. 1 of these drawings is a longitudinal section of a hydraulic pump established according to a first embodiment of the invention;

FIG. 2 is a section along II-II of FIG. 1;

FIG. 3 is a section along III III of FIG. l, the position occupied by the regulating plate of this pump corresponding to the maximum value of the delivery rate of the liquid delivered;

FIG. 4 is a section identical to the section shown in FIG. 3, the position of the regulating plate corresponding to an intermediate value of the delivery rate of the liquid delivered;

FIG. 5 is a diagram in perspective showing the forces which are exerted on the rotatable active unit of a pump according to the invention; and

FIG. 6 is a longitudinal section of a hydraulic pump established according to another embodiment of the invention.

The hydraulic pumps which will now be described by way of example are particularly intended to be mounted in aeronautical or aerospatial equipment.

As shown in FIGS. 1 and 6, such a pump comprises:

A casing 1,

A cylinder block 2, rotatable about a first axis XX and in which are provided cylinders 3 of axis parallel to this first axis XX and regularly distributed about this first axis XX,

A wobble plate 4, rotatable about a second axis YY intersecting the first axis XX and forming with this first axis XX an obtuse angle A,

And connecting means 5 for imperatively connecting in rotation the cylinder block 2 and the wobble plate 4, such connecting means 5 being advantageously constituted by a universal joint connecting system.

Drive means, such as a drive shaft 25, are then provided for driving in rotation the unit constituted by the cylinder block 2 and the wobble plate 4.

In each of the cylinders 3, a piston 6 is provided, slidable in the cylinder 3 and coupled yto one of the two ends of a rod 7 whose other end is coupled to the wobble plate 4, this coupling (rod 7-piston 6; rod 7-wobble plate 4) being realized by means of rotary joints 26.

Each of the variable volume chambers defined by a cylinder 3 and the corresponding piston 6 is then served,

For the admission, by an admission port 8 provided in the cylinder 3 and opening into an admission chamber 27.

And for the delivery, by a delivery valve 9 comprising an obturator member 28 constituted by a poppet (FIG. l) or a ball (FIG. 6) and return means urging this obturator member toward its closed position, these return means being constituted by a spring 29 (FIG. l) or by the action of the centrifugal force (FIG. 6).

This being the case, in accordance with the principal feature of this invention, the pump further comprises, in order to permit the delivery rate of the liquid delivered to be varied between a maximum value and a minimum value,

A rotatable collector 11, rigidly connected to the cylinder block 2 and provided with a delivery conduit 12 coaxial with the first axis XX, this delivery conduit 12 being in communication, by the intermediary of canals 30, with each of the variable volume chambers 10 when the delivery valve 9 is open, this delivery conduit 12 being connected, by the intermediary of a sleeve 13 ensuring annular liquid-tightness, to a delivery orifice 14 coaxial with the first axis XX and provided in the casing 1,

A regulating plate 15 perpendicular to the first axis XX and mounted so as to be able to turn about this first axis XX, this regulating plate 15 being provided with a groove 16 connected to a low pressure by the intermediary of canals 31 and extending over a circular arc of 180,

Counterbalancing shoes 17, each corresponding to a variable volume chamber 10, mounted in cylindrical housings 18 permanently connected to the corresponding variable volume chamber 10, each of these counterbalancing shoes 17 being provided with an orifice 19, each of these counterbalancing shoes 17 bearing against the regulating plate 15 such that the orifices 19 defile past the groove 16 of the regulating plate 15, directly opposite this groove 16,

And control means for turning the regulating plate 15 between a first extreme angular position for which the groove 16 is in communication with all of the variable volume chambers 10 in which the pistons 6 are performing their admission stroke, this first extreme angular position corresponding to the maximum value of the delivery rate of the liquid delivered by the pump, and a second extreme angular position for which the groove 16 is in communication with all or some of the variable volume chambers 10 in which the pistons 6 are performing their delivery stroke, this second extreme angular position corresponding to the minimum value of the delivery rate of the liquid delivered by the pump.

With regard to the minimum value of the delivery rate of the liquid delivered by the pump, in particular in the aeronautical and aerospatial domain of application of these pumps, this value is generally zero, or very small, that is to say corresponding to the rate of leakage of the apparatus in which the pump is incorporated.

In these conditions, when the regulating plate 15 occupies its second extreme angular position, the groove 16 is in communication with all of the variable volume chambers 10 in which the pistons 6 are performing their delivery stroke.

In FIGS. 3 and 4, the variable volume chambers in which the pistons are performing their admission stroke are situated on the right of the longitudinal plane of symmetry P of the pump; whereas the variable volume chambers in which the pistons are performing their delivery stroke are situated on the left of this longitudinal plane of symmetry P.

In FIG. 3, the regulating plate 15 is shown in its first extreme angular position (maximum value of the delivery rate of the liquid delivered by the pump).

In FIG. 4, the regulating plate 15 is shown in an interf mediate position (intermediate value of the delivery rate of the liquid delivered by the pump).

Certain advantageous features will now be described, which are applied to the pumps established according to the embodiments illustrated in FIGS. 1 4 and in FIG. 6.

With regard to the counterbalancing shoes 17, they are each applied against the regulating plate 15 by a resultant force generated by a spring 20 and by the action of the pressure (admission pressure or delivery pressure) on the sections of the counterbalancing shoes 17 exposed to f this pressure.

According to the embodiment illustrated in FIG. 1, the sleeve 13 is rotatable and comprises an annular bearing surface 21 perpendicular to the first axis XX and maintained applied against a fixed annular track 22 by a resultant force generated by the action of a spring 23 and by the action of the pressure (delivery pressure) on the sections of the sleeve 13 exposed to this pressure.

According to the embodiment illustrated in FIG. 6, the sleeve 13 is non-rotatable and comprises an annular bearing surface S1 perpendicular to the first axis XX and maintained applied against a rotatable annular track 52, belonging to the rotatable collector 11, by a resultant force generated by the action of a spring 53 and by the action of the pressure (delivery pressure) on the sections of the sleeve 13 exposed to this pressure.

Concerning the cylindrical housings 18 in each of which is mounted a counterbalancing shoe 17, they can be provided,

Either in the collector 11, as shown in FIG. 1,

Or in the cylinder block 2, as shown in FIG. 6.

As for the permanent connection which must exist between each cylindrical housing 18 and the corresponding variable volume chamber 10, itis ensured,

Either by a canal 24 provided in the constituent poppet of each delivery valve 9, as shown in FIG. 1,

Or by a canal 54 provided in the seat co-operating with the constituent ball of each delivery valve 9, as shown in FIG. 6.

For turning the regulating plate 15 from its first extreme angular position to its second extreme angular position, although control means can be used which are operated manually, it seems preferable (particularly in the domain of application envisaged by way of example) to use control means which are controlled by the delivery pressure of the pump.

For this purpose, as shown in FIG. 2, these control means are constituted by,

A toothed wheel 32 angularly fixed on a shaft 33 rigidly connected to the regulating plate 15 and meshing with a rack 34,

A single-acting jack 35 urged on one side by a spring 36 and on the other side by the pressure of a control uid,

And a distributor device 37 controlled by the delivery pressure of the pump and controlling the inlet or the outlet of the control uid in the single-acting jack 35.

In FIG. 5, a perspective diagram shows the forces which are exerted on the cylinder block 2-collector 11 unit of the pump established according to the embodiment illustrated in FIG. l, these two pieces, as well as the regulating plate 15, being shown schematically and separated apart from one another in order to facilitate the understanding of this diagram.

`In the cylinder block 2, the cylinders 3 have been indicated, which have been assumed to be ten in number, whereas in the collector 11, the counterbalancing shoes 17 have been indicated, which are then also ten in number. The cylinders 3 to which the index r has been assigned correspond to the delivery phase, whereas the cylinders 3 to which the index a has been assigned correspond to the admission phase.

Each piston which is performing a delivery stroke, exerts on the cylinder block 2-collector y11 unit a force fr directed in the direction from the cylinder block 2 towards the regulating plate 15, the resultant of these forces fr being the force FI, which is eccentric with respect to the iirst axis XX.

Each counterbalancing shoe corresponding to a cylinder 31F exerts on the cylinder block 2-collector `11 unit a force fe directed in the direction from the regulating plate towards the cylinder block 2,the resultant of these forces fe being the force Fe, which is eccentric with respect to the rst axis XX but coaxial with the resultant force Fr. The sum of the resultant forces Fr and Fe is thus a force Fr-Fe eccentric with respect to the iirst axis XX.

The delivery pressure exerts on the cylinder block 2- collector 11 unit, a force Fo directed in the direction from the regulating plate 15 towards the cylinder block 2 and coaxial with the rst axis XX.

Finally, the resultant of the forces Fr-Fe and FD is a force R, which is eccentric with respect to the rst axis XX, this force R being made as small as possible and being, preferably, directed in the direction from the regulating plate 15 towards the cylinder block 2.

This force Ris then received by a bearing 38 interposed between the collector 11 andthe casing 1.

In respect of the pump established according to the embodiment illustrated in FIG. 6, an identical diagram could be established, the force R, directed in the direction from the regulating plate 15 towards the cylinder block 2 being then received by a bearing 58 interposed between the collector 11 and the casing 1.

A hydraulic pump established according to this invention possesses characteristics of lightness, reliability of operation and correct behaviour at relatively high operating temperatures, which render this pump particularly apt to be mounted in aeronautical or aerospatial equipment.

What is claimed is: 1. A hydraulic pump comprising: a casing, a cylinder block rotatable about a first axis and in which are provided cylinders of axis parallel to this first axis, these cylinders being regularly distributed around said rst axis, wobble plate rotatable about a second axis intersecting the first axis and forming with said lirst axis an obtuse angle, connecting means for positively connecting the cylinder block and the wobble plate together in rotation, pistons slidable in the cylinders and each coupled at one of their ends to a rod whose other end is coupled to the wobble plate,

admission ports and delivery valves for serving, respectively for the admission and for the delivery, each of the variable volume chambers defined by a cylinder and the corresponding piston,

and drive means for driving in rotation the unit formed by the cylinder block and the wobble plate,

said pump further comprising, in order to permit the delivery rate of the liquid delivered to be varied between a maximum value and a minimum value,

a rotatable collector, rigidly connected to the cylinder block and provided with a delivery conduit coaxial with the first axis, this delivery conduit being in communication with each of the variable volume cham- -bers when the delivery valve is open, this delivery conduit being connected, by the intermediary of a sleeve ensuring annular liquid-tightness, to a delivery orifice coaxial with the rst axis and provided in the casing,

a regulating plate perpendicular to the first axis and mounted so as to be able to turn about this first axis, this regulating plate being provided with a groove connected to a low pressure region of the pump by the intermediary of canals, this groove extending along a circular arc of at the most,

counterbalancing shoes, each corresponding to a variable volume chamber, mounted in cylindrical housings permanently connected to the corresponding variable volume chamber, each of these counterbalancing shoes being provided with an orifice, each of these counterbalancing shoes bearing against the regulating plate such that their orifices pass in front of the groove of the regulating plate, directly opposite this groove,

and control means for turning the regulating plate between a rst extreme angular position for which the groove is in communication solely with the variable volume chambers in which the pistons are performing their admission stroke, this rst extreme angular position corresponding to the maximum value of the delivery rate of the liquid delivered by the pump, and a second extreme angular position for which the groove is in communication with all or some of the variable volume chambers in which the pistons are performing their delivery stroke, this second extreme angular position corresponding to the minimum value of the delivery rate of the liquid delivered by the pump.

2. A pump according to claim 1, in which the minimum value of the delivery rate of the liquid delivered by the pump is zero, wherein the groove provided in the regulating plate extends along a circular arc of 180, and the control means of the regulating plate are arranged so that when sald regulating plate occupies its second extreme angular pos1t1on, the groove is in communication with all of the variable volume chambers in which the pistons are performing their delivery stroke.

3. A pump according to claim 1, wherein the counterbalancing shoes are each applied against the regulating plate by a resultant force generated by a spring and by the action of the admission pressure or delivery pressure on the sections of the counterbalancing shoe exposed to this pressure.

4. A pump according to claim 1, lwherein the sleeve is rotatable and comprises an annular bearing surface perpendicular to the iirst axis and maintained applied against a dixed annular track by a resultant force generated by the action of a spring and by the action of the delivery pressure on the sections of the sleeve exposed to this pressure.

5. A pump according to claim 1, wherein the sleeve is non-rotatable and comprises an annular bearing surface perpendicular to the first axis and maintained applied against a rotatable annular track, belonging to the rotatable collector, by a resultant force generated by the action of a spring and by the action of the delivery pressure on the sections of the sleeve exposed to this pressure.

. 6. A pumpaccording to claimll, wherein the cylindrical housings in each of which is mounted a counterbalancing shoe are provided in the collector.

7. A pump according to claim 1, wherein the cylindrical housings in each of which is mounted a counterbalancing shoe are provided in the cylinder block.

8. A pump according to claim 1, wherein each cylindrical housing and the corresponding variable volume chamber are interconnected by a canal provided in the constituent poppet of each delivery valve.

9. A pump according to claim 1, wherein each cylindrical housing andthe corresponding variable volume chamber are interconnected by a canal provided in the seat co-operating with the constituent ball of each delivery valve.

10.. A pump according to claim 1, wherein the control means co-operating with the regulating plate are controlled by the delivery pressure of the pump.

l References Cited UNITED STATES PATENTS 4/1929 Carey 103-162 1/1961 Dudley 103-162 v10/1965 vvBadenoch et al `103-'162 7/1965 Schottler 1031-162 1/1966 Schott 103-162 ,FOREIGN PATENTS 3/1964 France 10S-@162 WILLIAM L. FREEH, Primary Examiner U.S. Cl. X.R. 

